Hydraulic driving apparatus for working machine

Patent metadata

Field	Value
Publication number	US-9777750-B2
Application number	US-201514634046-A
Country	US
Kind code	B2
Filing date	Feb 27, 2015
Priority date	Mar 10, 2014
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

Provided is a hydraulic driving apparatus including a calculation section calculating a temporary target engine rotation speed corresponding to an engine operation amount, a calculation section calculating a temporary target pump displacement volume based on first-control and second-control target pump displacement volumes corresponding to an actuator operation amount and a pump load pressure, and a command section calculating a final target engine rotation speed and a final target pump displacement volume to output commands. The command section calculates a target pump discharge amount from the temporary target engine rotation speed and the temporary target pump displacement volume, sets the final target pump displacement volume to one larger than the temporary target pump displacement volume, and sets the final target engine rotation speed to one being lower than the temporary target engine rotation speed and allowing a pump discharge amount equivalent to the target pump discharge amount to be obtained.

First claim

The invention claimed is:

1. A hydraulic driving apparatus for a working machine, comprising:
an engine;
at least one variable displacement hydraulic pump driven by the engine to discharge a hydraulic fluid;
a hydraulic actuator supplied with the hydraulic fluid discharged by the hydraulic pump to be thereby actuated;
an engine operation member to which an operation for specifying a target rotation speed for the engine is applied;
an actuator-operation member to which an operation for specifying a speed of actuation of the hydraulic actuator is applied;
a pump-load-pressure detector that detects a load pressure on the at least one hydraulic pump;
an engine-operation detector that detects an amount of the operation applied to the engine operation member;
an actuator-operation detector that detects an amount of operation applied to the actuator operation member; and
a controller that outputs a command for a pump displacement volume of the at least one hydraulic pump and a command for a rotation speed of the engine, based on the pump load pressure detected by the pump-load pressure detector and the amounts of respective operations detected by the engine-operation detector and the actuator-operation detector, wherein:
the controller includes: a temporary-target-engine-rotation-speed calculation section that calculates a temporary target engine rotation speed corresponding to the amount of operation applied to the engine operation member; a temporary-target-pump-displacement-volume calculation section that calculates a first-control target pump displacement volume corresponding to the amount of the operation applied to the actuator operation member and a second-control target pump displacement volume corresponding to the pump load pressure and selects a smaller one of the first-control target pump displacement volume and the second-control target pump displacement volume as a temporary target pump displacement volume for the at least one hydraulic pump; and a command section that calculates a final target engine rotation speed and a final target pump displacement volume based on the temporary target engine rotation speed and the temporary target pump displacement volume and outputs commands for the engine rotation speed and for the pump displacement volume based on the final target engine rotation speed and the final target pump displacement volume;
in the case where the temporary target pump displacement volume is larger than a maximum pump displacement volume of the at least one hydraulic pump, the command section performs setting the final target engine rotation speed to the temporary target engine rotation speed and setting the final target pump displacement volume to the maximum pump displacement volume; and
in the case where the temporary target pump displacement volume is equal to or smaller than the maximum pump displacement volume of the at least one hydraulic pump, the command section performs: calculating a target pump discharge amount for an amount of hydraulic fluid discharged by the at least one hydraulic pump based on the temporary target engine rotation speed and the temporary target pump displacement volume: setting the final target pump displacement volume to a volume which is larger than the temporary target pump displacement volume and which is equal to or smaller than the maximum pump displacement volume; and setting the final target engine rotation speed to a specific engine rotation speed lower than the temporary target engine rotation speed, the specific engine rotation speed allowing a pump discharge amount equivalent to the target pump discharge amount to be obtained with the final target engine rotation speed and the final target pump displacement volume.

2. The hydraulic driving apparatus for a working machine according to claim 1 , wherein the command section sets the final target engine rotation speed to a value obtained by dividing the target pump discharge amount by the maximum pump displacement volume, in the case where the temporary target pump displacement volume is equal to or smaller than the maximum pump displacement volume of the at least one hydraulic pump.

3. The hydraulic driving apparatus for a working machine according to claim 1 , wherein the command section sets the final target engine rotation speed to a value not lower than a preset minimum target engine rotation speed.

4. The hydraulic driving apparatus for a working machine according to claim 1 , wherein the command section sets the final target pump displacement volume so as to prevent a pump absorption torque corresponding to the final target pump displacement volume from exceeding a preset maximum torque.

5. The hydraulic driving apparatus for a working machine according to claim 1 , wherein the command section performs control including suppressing a fluctuation in the final target engine rotation speed regardless of a fluctuation in the temporary target pump displacement volume, in the case where the final target engine rotation speed is equal to or higher than the set value.

6. The hydraulic driving apparatus for a working machine according to claim 1 , wherein the at least one hydraulic pump includes a plurality of hydraulic pumps, and the controller calculates the first-control target pump displacement volume, the temporary target pump displacement volume, the target pump discharge amount, and the final target pump displacement volume individually for each of the plurality of hydraulic pumps.

Assignees

• Kobe Steel Ltd
• Kobelco Constr Mach Co Ltd

Inventors

• Sugano Naoki
• Igaue Takayuki
• Hirozawa Mitsunori

Classifications

• F15B13/042

  operated by fluid pressure {(F15B13/0401, F15B13/0416 take precedence)} · CPC title

• F15B2211/6652

  Control of the pressure source, e.g. control of the swash plate angle · CPC title

• F15B2211/2656

  by control of the pumps · CPC title

• E02F9/2246 Primary

  Control of prime movers, e.g. depending on the hydraulic load of work tools · CPC title

• F15B2211/20546

  variable capacity · CPC title